1. Field of the Invention
The present invention relates to coil means having a drum core for winding a coil wire and a ring core encircling the drum core, the drum core and the ring core being supported on a base.
2. Description of the Prior Art
A conventional coil means which may be used in a transformer includes a drum core having a drum portion and a pair of flanges provided at the opposite ends of the drum portion. A coil wire or coil wires are wound around the drum portion and a ring core is provided to encircle the drum core and the wire or wires wound around the drum core. The drum core with the coil wire and the ring core are supported at one ends by a base plate which made of a non:magnetic material such as a plastic material. The drum core and the ring core are then adhesively attached to the base plate.
It has been experienced in this type of coil means that locating and assembling the drum core and the ring core on the base plate are not convenient. Since the ends of the drum core and the ring core are simply placed on a flat surface of the base plate, the drum core may be displaced on the surface of the base plate during assembling. This may cause a difficulty in fitting the ring core in position. If the ring core is nevertheless fitted forcibly, there may be a possibility that the drum core and/or ring core may be damaged resulting in a change in the magnetic property of the coil means.
It should further be pointed out that in this type of coil means coil wire ends may be put between the ring core and the periphery of the flange of the drum core and may sometimes be cut during the assembling operation. A further problem encountered in this known type of coil means is that it was difficult to make the coil means sufficiently small in height.